Tesla said batteries developed with Panasonic will power its coming Model X sport-utility vehicle.

Electric-car maker Tesla Motors Inc. said it entered an agreement with electronics giant Panasonic Corp. to boost the supply of lithium-ion batteries to meet the increased production of Tesla’s current and coming vehicles.

The deal continues a long collaboration between the companies aimed at developing advanced automotive battery cells that could help expand the market for electric vehicles. The Palo Alto, Calif., car company said it will use the batteries to power its Model S sedan and the Model X, a performance SUV it expects to begin building by the end of next year.

“This expanded agreement with Panasonic is important to Tesla as we continue to increase the pace of production,” said Tesla CEO Elon Musk. “We look forward to strengthening our relationship with Panasonic, and I’m confident that this partnership will continue to be an integral part of Tesla’s success for years to come.”

Tesla said Panasonic’s cylindrical battery cells, which it designed specifically for high performance and long life under the demands of electric vehicles, are a critical element in the 265-mile range of its Model S sedan.

Concerns about the availability, performance and longevity of batteries have kept many consumers from considering electric cars. Expanded production resulting from the deal between Tesla and Panasonic could help accelerate mainstream acceptance of electric cars.

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